Citrus peel oils are generally prepared by expression of the essential oils from the peel of citrus fruits, such as grapefruit, oranges, and the like. The essential oils are generally contained in numerous oval sacs which are irregularly distributed in the outer colored portion or "flavedo" portion of peel. During expression, the sacs are mechanically ruptured (e.g., by crushing the peel) and the oils contained in the sacs are liberated and collected as an aqueous slurry along with cell water and cell debris. The citrus peel oil is separated and clarified by decantation, centrifugation, filtration, or similar process. Especially with oranges, the citrus peel oil can also be prepared by a so-called de-oiling process whereby the entire outer peel portion of the whole fruit is lightly cut or pricked by a scarifier device. The cuts or pricks allows the peel oil to exude from the sacs and out of the peel. The exuded peel oil is then washed off the fruit, collected, and then separated and clarified in the same or similar manner as for expressed peel oil. The de-oiling process is often used to limit the amount of citrus peel oil in the extracted juice.
Citrus peel oils are usually high in aroma and flavor components derived from and associated with the particular fruit. Such citrus peel oils, which generally contain up to about 90 weight percent d-limonene, are used as flavoring additives in bakery goods, soft drinks, citrus juices, and the like. Such citrus peel oils may also be used as additives in non-food products such as perfumes, soaps, cosmetics, lotions, and the like. Orange peel oil is often used as an additive for orange juice concentrate and orange juice to enhance the aroma and flavor.
Unfortunately, low but significant levels of pesticides can often be found in citrus peel oil. It appears that at least some pesticides are absorbed from the soil by the tree roots and then concentrated in the fruit peel. Pesticides, if applied during the fruit formation period, may also be directly absorbed into the peel. During expression or de-oiling processes, the pesticides may be released along with, and thus contained in, the resulting citrus peel oil. Depending on the specific levels of pesticides present, the value and usefulness of the citrus peel oil can be significantly reduced.
Pesticides are generally not found to a significant extent in the non-peel portion of citrus fruits. Thus, unless a significant amount of the peel oil is released during juice extraction or is added back to the juice product at a later time, pesticide contamination of the citrus juice produced is generally at a relatively low level.
Nonetheless, on occasion higher than desirable levels of pesticides may be found in the juice product or the stripper oil derived from such juice. Stripper oil (sometimes also referred to as oil phase essence) is the volatile material removed from the raw juice prior to preparing the orange juice concentrate by evaporative concentration. The stripper oils, which contain aroma and flavor volatiles, are generally added back to the concentrated orange juice to enhance the aroma and flavor characteristics. U.S. Pat. Nos. 4,973,485, 3,248,233, 2,641,550, and 2,573,699 (all of which are incorporated by reference) describe illustrative processes for preparing concentrated orange juice where the volatiles (i.e., stripper oil) are first removed and then added back to the concentrated juice.
Attempts to reduce the amount of pesticides in citrus peel oil and the like have essentially been limited to efforts to reduce the level of pesticide use and/or provide biodegradable pesticides. To this end, some pesticides have been totally banned for use on citrus trees in the United States. The use of other pesticides has been limited in regard to the amount which can be applied and/or the time in the growing cycle in which the pesticides can be applied. Although banning or use restrictions for certain pesticides can reduce the levels of pesticides in the peel, and ultimately in the citrus peel oil, it may (and likely will) also reduce the overall fruit and juice yields as well as the quality of the fruit and resulting juice due to insect and other crop damage. Although the development of biodegradable pesticides appears promising, such pesticides are unlikely to completely eliminate the need for the non-biodegradable pesticides currently in use. Thus, the use of pesticides in the citrus industry--even if significantly restricted and regulated--is expected to continue for the foreseeable future.
Since it is not possible in the foreseeable future to completely eliminate the use of pesticides in the citrus industry, other approaches are needed to remove pesticides from such citrus oils (especially from citrus peel oils). It would be desirable, therefore, to provide a method by which the levels of pesticides present in raw citrus peel oils and/or raw stripper oils could be significantly reduced. It would also be desirable to provide an essentially pesticide-free citrus peel oil, especially an essentially pesticide-free orange peel oil. It would also be desirable to provide an essentially pesticide-free citrus peel oil with improved aroma and flavor characteristics. The present invention provides such processes and citrus oils.